UK light-heavyweight Buatsi made a winning yet underwhelming start to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a close ten-round fight at the Co-op Live Arena.
But the challenger found success, landing some telling single shots in a fight where the approaches failed to mesh, with constant grabbing marring the action.
The officials judged it 96-94 to Buatsi, with the final judge a 95-95.
"It wasn't my greatest showing but what defines champions? They prevail," the victor stated in the arena as he was greeted with boos from the crowd.
The British fighter bounced back after his maiden career setback - an memorable fight with Callum Smith in February - to earn a 20th career victory.
Several boxing experts felt the challenger, 31, deserved the victory but the Derbyshire fighter suffered the second setback of his 28-fight professional journey.
The Champion Earns Triumph in Dull Affair
The fighter's advancement has stalled in recent years through contract problems and extended periods of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to achieve expectations - maybe in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with neither fighter prepared to be aggressive in a tentative initial rounds.
The challenger, whose only previous defeat came at super middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second bout at the higher weight class.
By the fight's midpoint, Parker had made it competitive, causing problems for Buatsi, who worked behind a protective stance to barely take the cleaner stanzas.
The crowd's patience diminished because of frequent holding, with Parker slipping to the canvas several times during close exchanges.
Parker ended stronger, but multiple periods were challenging to assess. However, former world champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the caliber of heavy hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Inspires Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Bradley Rea by close verdict in a terrific Manchester vs Manchester battle to win the European light heavyweight championship.
The arena grew hushed for a extremely emotional tribute prior to the bout as a bell ceremony rang in remembrance of local hero Hatton, who succumbed aged 46 in recently.
It was the first major televised fight night in the location since Hatton's passing. As the concluding sound ended, the stillness became a roar of "there's just one Ricky Hatton".
The fighting during the bout equaled the sentiment. The eventual winner was floored by a powerful punch directly to the chin in the second round, getting up unsteadily to his position on the referee's count.
But the Manchester United-red equipment of the fighter soon advanced again. Across the ring, Rea - in opposing blue - was marked up quickly, significant bruising appearing under his eye as the pair exchanged punishing blows.
The challenger, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with effective uppercuts as the intensity hardly diminished over twelve rounds.
The victor barely secured the result with scoring tallies of even score, close margin and wider gap, but the two athletes were persistent and brave, all the qualities their hero the legend stood for.
